Electrotinning



ae-see.

" LOUIS SCHULTE, OF

CHICAGO, ILLINOIS.

amcrnormnme.

. K0 Drawing. Application filed July 12,

To all whom it may concern Be it known that I, LoUIs SCHULTE, a citizen of the United States of America, a resident of Chicago, in the county of Cook, State of Illinois, have invented certain new and useful Improvements in Electrotinning,

of which the following is a full, clear. and

exact description.

This invention relates to improvements in electro-tinning, and more particularly to a solution and a method whereby electro-tinning can be successfully carried out on a commercial scale and in an economical manner. The invention also includes a new article made by the new process.

In the electrodeposition of tin, great difficulty has been experienced in producing heavy, dense and coherent deposits. The difficulties involved in electro-tinning are well known in this art, and they are evidenced by the fact that, although various formulas for electro-tinning have been published and a few patents granted, no commercial electro-tinning is available up to the present time.

I have discovered a solution and method by which electrotinning can be done without difficulty and this solution, which will be hereafter fully described, may successfully be used with different concentration and without causing a formation of colloidal or spongy deposit. It will be understood by those skilled in the art that the thickness of deposit or the amount of tin plated per square foot depends upon the length of time and amount of amperes used. I prefer to use from 1 to 2 volts and to have about 10% to 20% of anode surface in proportions to cathode surface. With these proportions I have found that the solution with a slight acid reaction is practically self-sustaining.

In carrying out my invention in its preferred form, I dissolve one pound of caustic. potash (KOH) in about two quarts of water, I to this I add partly diluted commercial hy-l drofluoric acid (HF) untilacid reaction is obtained and then add suflicient water to make one gallon in all. In this solution of potassium fluoride with a slight excess of hydrofluoric acid I suspend metallic tin as an anode on a positive bus bar, and on the negative bus bar I connect metal strips surrounded by porous cups and with the aid of the electric current dissolve the metallic tin until the solution has absorbed approximate ly one ounce of tin per gallon of fluid when I Specification of Letters Patent.

Patented July 25, 1922.

1920. Serial No. s95,ss2.

remove the porous cups and metal strips and suspend articles, sheet copper for instance, from the negative bus bar, thereby plating the copper with tin.

Instead of using the electric current in connection with porous cups for dissolving and saturating a new solution, I may add any soluble tin salt, chloride for instance, to the solution.

In the foregoing description I refer to a tin solution in a concentrated form with an acid reaction, but a solution also can be used in a neutral as well as an alkaline state, and I prefer the. neutral or alkaline state in cases where tin is to be deposited on articles made of sheet zinc, zinc castings or on galvanized lIOIl parts. I

The above solution has been proven entirely satisfactory for this purpose, therefore I do not limit myself to the above given formula, as my process may be used with 'various modlfications for numerous The copper sheets of any desired gauge and size are first cleaned in any suitable manner, such as by pickling, rinsing or scouring, and these clean sheets are suspended in the tin solution.

If it is desirable to tin the sheets on one sideonly, I secure two sheets together with their flat faces in contact, thereby protecting these contacting faces from the action of the tin solution.

After plating the sheets with the desired amount of tin, I remove them from the tinning solution and rinse them in water. Thereafter, the sheets are preferably passed between and subjected. to the pressure of heated rollers, which will dry the sheets and, at the same time improves the tin-by forming a closer grained structure of the tin, or in other words, thetin is tempered as in case hardening.

of electric current from an acid solution contalmng 'potasslum fluoride and stannous fluoride.

stannous fluoride,

comprising the tinning of copper by means 3. A process of the character described comprising the tinning oiicopper by means of electric current from a solution containing potassium fluoride and stannous fluoride-and a slight excess of hydrofluoric acid.

4. A process of the character described comprising the plating of metal articles with. tin from an acid solution containing potassium fluoride and fluoride of tin to which licorice root extract is added.

5. A plating electrolyte comprising a solution containing potassium fluoride,

and a slight excess of hydrofluoric acid.

In testimony that I claim the foregoing I hereunto aflix my signature.

LOUIS SCHULTE. 

